Process for the preparation of alpha-nitro-isobutene



Patented Mar. 11, 1947 UNITD STATES PROCESS FOR THE PREPARATION OF a-NITRO-ISOBUTENE Arthur Ernest Wilder Smith and Scaife, Norton-on-Tee Imperial Chemical In poration of Great Brit N Drawing.

Application ATENT OFFICE Charles William 5, England, assignors to dustries Limited, a corain February 22, 1945,

Serial No. 579,310. In Great Britain March 13, 1944 8 Claims. (01. 260644) process for the prepdinitro-isobutane, although a larger amount than this may also be used. When a mixture of substances is used, an amount of the mixture equivalent to one mole of nitrous acid per mole of 1,2- dinitro-isobutane should be used.

sure.

The preferred basic substances are the oxides and hydroxides of the alkali metals and amof the alkali metals are little less eificient. It will generally be lesirable to carry out the reaction in the presence excess of Water, relative to the 1,2-dinitrosobutane. Good results can be obtained by using later as the sole medium and employing the 1,2- initro-isobutane as a suspension in it, but a olvent for the 1,2-dinitro-1'sobutane may be presnt if desired. It will generally be preferable 1 employ the 1,2-dinitro-isobutane in commiuted form. In carrying out the reaction it is asirable to stir the reaction mixture.

In the reaction a small amount-generally less Ian %of l-nitro 2-methyl propene-2 is produced. For many purposes it is unnecessary to free the a-IlltlO-lSObLltEIle from this, but when pure oz-IlltI'O-lSOblltBIlB is required it can be proploying a column with a sufiicient number of plates, or an equivalent packed column. At substantially 15 mm. of mercury I-nitro 2-methyl propene-2 distils ofi at 4043 C. and a-nitro-isobutene at 59-62 C.

The invention is illustrated but not limited by the following examples:

Example 1 Example 2 10.0 gms. of 1,2-dinitro-isobutane were suspended in ccs. water and 6.75 gms. calcium carbonate added. After stirring for 20 hours the mixture was treated as in Example 1, and yielded 0.75 gms. u-nitro-isobutene.

Example 3 10.0 gms. of 1,2-dinitro-isobutane were suspended in 100 solution was treated as in Example 1, and yielded 1.1 gms. e-nitro-isobutene.

Example 4 Example 5 16.3 gms. of 1,2-dinitro-isobutane were sus pended in ccs. water and 8.71 gms. ammonium bicarbonate added. After stirring for 1 hours the solution was treated as in Example 1, and yielded 8.22 gms. cz-l'lltIO-iSObllt-BIIG.

Example 6 10.0 gms. of 1,2-dinitro-isobutane were susp nded in 100 ccs. water and 1.9 gms. calcium hydroxide with stirring over /4 hour. lution was treated as in Example 1, and yielded Example 7 10.0 gms. of 1,2-dinitro-isobutane were suspended in 100 cos. of water and 2.74 gms. zinc oxide added with stirring. After hours the mixture Was treated as in Example 1, and yielded 1.96 gms. a-nitro-isobutene.

Emample 8 10.0 gms. of 1,2-dinitro-isobutane were suspended in 100 cos. of water and 3.85 gms. of ammonium carbonate added. After stirring for 1 hour the solution was treated as in Example 1, and yielded 2.15 gms. a-nitro-isobutene.

Example 9 100 gms. of 1,2-dinitro-isobutane were suspended in 200 ccs. water and 27 gms. of sodium dissolved in 100 ccs. of Water added After /2 hour the so- 53.''! gms. of a-nitro-isobutene.

We claim:

1. A process for the production of alpha-nitrovisobutene which comprises treating 1,2-dinitroisobutane in the presence of water with at least one basic substance selected from the group consisting of the oxides, hydroxides, carbonates and bicarbonates of the alkali metals and alkaline earth metals and ammonium hydroxide and ammonium carbonate.

2. A process according to claim 1 where the total amount of such basic substance used is at least stoichiometrically equivalent to the amount of 1,2-dinitro-isobutane reactant used.

3. A process according to claim 1 where the treatment is carried out at a temperature lower than C.

4. A process according to claim 1 including the steps of separating the alpha-nitro-isobutene with a volatile solvent, drying the extract, removing the volatile solvent by distillation and distilling the residue under reduced pressure.

5. A process according to claim 1 where the alpha-nitro-isobutene is separated from the reaction products by extracting alpha-nitro-isobutene with a volatile solvent, drying the extract, removing the volatile solvent by distillation, distilling the residue under reduced pressure, and fractionally distilling the product under reduced pressure to remove l-nitro-Z-methyl propene-Z.

6. A process for the production of alpha-nitroisobutene which consists of treating 1,2-dinitro isobutane in the presence of water with an alkali metal hydroxide.

7. A process for the production of alpha-nitroisobutene which consists of treating 1,2-dinitroisobutane in the presence of Water with ammonium hydroxide.

8. A process for the production of alpha-nitroisobutene which consists of treating 1,2-dinitroisobutane in the presence of water with ammonium bicarbonate.

ARTHUR ERNEST WILDER SMITH. CHARLES WILLIAM SCAIEE.

REFERENCES CITED Hass et al., Chemical Reviews, 411 (1943).

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